1. Field of the Invention
The present invention relates to a display device, and more particularly to a display device with a substantially flat organic layer.
2. Description of the Related Art
Among different types of flat panel displays, organic light emitting diode (OLED) has become popular due to its desirable characteristics such as low driving voltage, slim design, light weight, a wide viewing angle, and a quick response time. OLED is generally classified into a passive-matrix type and an active-matrix type depending on the driving method. In the active-matrix OLED, each thin film transistor thin film transistor is connected to a pixel area to control the organic light-emitting layer's emission by pixel areas. A pixel electrode is disposed in a pixel area and electrically separated from the adjacent pixel electrodes so that it can be driven independently. A wall higher than the pixel electrode is formed between the pixel areas to prevent the pixel electrodes from being short-circuited or accidentally coupling multiple pixel areas. On the pixel electrodes between the walls, a hole-injecting layer and the organic light-emitting layer are formed sequentially.
Where the hole-injecting layer and the organic light-emitting layer contain a polymer, they are usually formed by an ink-jet method. However, ink-jet method does not always result in the optimal layers. For example, the thickness of the hole-injecting layer and the organic light-emitting layer around the wall is greater than desired when the layers are formed with the ink-jet method. This excessive thickness around the wall compromises the uniformity of brightness and reduces the lifespan of the display.